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The development of anode materials with a high capacity, excellent rate capability, and acceptable stability for sodium-ion batteries (SIBs) is still an urgent issue. Here, we fabricated FeS nanoparticle (NP)/three-dimensional (3D) carbon nanofiber aerogels (CNA) composites utilizing Fe-alginate aerogels as the renewable precursor. In the FeS/CNA sample, well-distributed FeS NPs were embedded on a 3D-CNA network with high electron conductivity and a large specific surface area. Impressively, the FeS/CNA sample was evaluated as an anode electrode material for SIBs, and exhibited an excellent specific capacity (473 mA h g−1 at 0.1 A g−1) and outstanding rate capacity (291 mA h g−1 at 5 A g−1). In addition, 97.4% of the capacity, 385 mA h g−1, was retained over 400 cycles at 2 A g−1, indicating the prominent cycling stability of the FeS/CNA sample. The results were ascribed to the unique structure of the FeS particles embedded on interconnected CNAs, which could boost sodium ion diffusion and facilitate electrolyte access. • Fe-alginate aerogels assure uniform dispersion of FeS NPs on porous carbon matrix. • 1D carbon fibers as transport channels can constitute porous 3D porous network. • FeS NPs and 3D network CNAs have a synergistic effect on sodium storage. • The FeS/CNA electrode reveals an excellent and stable electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract The FeCoNi(CuAl) 0.8 Ga 0.06 high-entropy alloy (HEA) was prepared by the vacuum arc melt casting method, then annealed at different temperatures for 1 h. The microstructure, phase constitution, and magnetic and mechanical properties of the FeCoNi(CuAl) 0.8 Ga 0.06 HEA during the phase transition were investigated. The experimental results showed that the as-cast alloy consisted of FCC and BCC duplex phases, and there were numerous nano-precipitates uniformly distributed in the BCC matrix. After annealing at different temperatures, the phase transformed from FCC to BCC. The relative volume fraction of the BCC phase increased, and the size of the nano-precipitates in the BCC matrix were larger after annealing than that of the as-cast sample. STEM-EDS images showed that there was a Cu-rich zone in the phase boundary region between FCC and BCC phases, and annealing may have significant influence on this region. Based on XRD, SEM, TEM and STEM-EDS results, a phase transition mechanism was proposed, which may have a close relationship with the Cu-rich nano-precipitates in the BCC matrix and the Cu-rich zone in the phase boundary region. In addition, it was found that the volume fraction of BCC (or FCC) phase can govern the magnetic properties. This study may help to deepen the fundamental understanding of the phase transition mechanism in HEAs. Graphical abstract Image 1 Highlights • Phase transition from a FCC structure to a BCC structure occurred during annealing. • Phase transition has a relation with the Cu-rich zone in the phase boundary region. • A phase transition mechanism was proposed based on the results of experiments. • The volume fraction of BCC (or FCC) phase can govern the magnetic properties. [ABSTRACT FROM AUTHOR]

The photoelectrocatalytic (PEC) oxygen evolution reaction (OER) is one of the most efficient ways for utilizing solar energy for water electrolysis. Nevertheless, up to now, the PEC conversion efficiency of the established photoanode is still low. In this work, α -Fe 2 O 3 /NiFe layered double hydroxide (LDH) photoanodes were synthesized by electrodeposition of LDH on α -Fe 2 O 3 . Compared with bare α -Fe 2 O 3 , the α -Fe 2 O 3 /Ni 0.5 Fe 0.5 -LDH photoanode displays about 3 times photocurrent enhancement and excellent long-term stability. The enhanced PEC activity of α -Fe 2 O 3 /NiFe-LDH is ascribed to the interface between α -Fe 2 O 3 and NiFe-LDH which can facilitate charge transfer and improve carrier density. Simultaneously, NiFe-LDH as a co-catalyst can accelerate the surface OER kinetics. [ABSTRACT FROM AUTHOR]

The silver loaded adsorbents has been demonstrated to be an exciting approach towards Hg 0 removal from natural gas streams, its Hg 0 removal efficiency and capacity is closely related to the valence state, particle size and dispersity of silver particles. This study focused on chemical reduction methods in aqueous solutions to synthesize Ag/4A zeolite, and the influences of ultrasonic and protective additives were investigated to reduce the size of silver particles. The characterization results showed that silver particles are loaded on the surface of 4A zeolite with highly dispersed elemental form, ultrasonic and addition of stearic acid as protective additives are the effective ways to produce small nano-scale silver particles close to 15 nm. Meanwhile, the silver particles on the surface of Ag/4A zeolite are the active sites for Hg 0 adsorption which can react with Hg 0 to form Ag-Hg amalgam alloy. The silver lattices disappeared from the outer boundary to the interior of the particles after Hg 0 adsorption, which indicated that the Hg 0 firstly reacts with the nano-scale silver on the surfaces and then gradually penetrates into the interior of silver particles. The Hg 0 removal efficiency of prepared Ag/4A zeolite adsorbents was higher than 96% after 200 min adsorption at 30 °C, and adsorption capacity reached to 5.985 mg/g. Furthermore, the regeneration and reutilization results indicated that the Hg 0 adsorption performance remained stable after 5 reuse cycles. [ABSTRACT FROM AUTHOR]

A new Ni-based superalloy with high-Cr content was designed for industrial gas turbines application. The microstructural homogenization and high-temperature cyclic oxidation behavior was investigated systematically. The results showed that the optimum heat treatment condition was 1563 K (1290 °C)/4 h + 1573 K (1300 °C)/6 h, A.C. (air cooling) + 1393 K (1120 °C)/2 h, A.C. + 1143 K (870 °C)/24 h, A.C., which can completely dissolve the γ/γ′ eutectic and the Ni 3 (TiTa) phase in the interdendritic region. The cyclic oxidation results showed that a multilayer of continuous and dense oxide-rich regions formed and the kinetic curves followed a parabolic law. The mass gain at 1323 K (1050 °C) and 1343 K (1070 °C) was 4.02 mg/cm 2 and 4.23 mg/cm 2 , respectively. No severe spallation of the oxide-rich region was observed. The outer layer of the oxide-rich region mainly consisted of Cr 2 O 3 , TiO 2 , and (Ni, Co)Cr 2 O 4 spinels, while the layer at the substrate-oxide interface was found to be Al 2 O 3 . The results show that this new superalloy has a better cyclic oxidation resistance at 1343 K (1070 °C) than the commonly used IN738 and GTD-111 superalloys. [ABSTRACT FROM AUTHOR]

HfMo 0.5 NbTiV 0.5 Si x (x = 0, 0.3, 0.5, 0.7) high-entropy alloys are synthesized by induction levitation melting with the aim of achieving a balanced combination of excellent strength at elevated temperature and reasonable ductility at room temperature (RT). The microstructure, phase evolution and compression mechanical properties of the alloys from 20 °C to 1200 °C are reported in this paper. It is found that the HfMo 0.5 NbTiV 0.5 matrix forms a simple disordered body-centered cubic (BCC) phase. After adding the Si element, multi-component silicide (Hf, Nb, Ti) 5 Si 3 is generated inside the alloys and exhibits a transition from hypoeutectic structure to eutectic structure and then to hypereutectic structure as the Si content increases. The addition of Si significantly improves the hardness and strength but reduces the ductility. At room temperature, The HfMo 0.5 NbTiV 0.5 and HfMo 0.5 NbTiV 0·5 Si 0.7 alloys show yield strengths of 1260 MPa and 2134 MPa, respectively, and the compressive mechanism transitions from ductile deformation to brittle fracture from x = 0 to x = 0.7. Strain softening and silicide segmentation are found to be typical during compression deformation of these alloys at elevated temperatures. In these conditions, the alloys survive at least 35% of engineering compression strain without fracture. During deformation at 1200 °C, the yield strengths of HfMo 0.5 NbTiV 0.5 and HfMo 0.5 NbTiV 0·5 Si 0.7 alloys are 60 MPa and 235 MPa, respectively. The attractive strength of the Si-containing alloys at elevated temperatures is strongly dependent on the strengthening effect caused by the silicides. [ABSTRACT FROM AUTHOR]